Plasma total homocysteine (tHcy) is an independent risk factor for arterial thrombosis and atherosclerosis in SLE. We investigated whether supplementation of SLE patients with a combination of 1 mg of B12, 5 mg of B6, and 1 mg of folate would lower their tHcy levels and thus potentially decrease their risk for associated vascular complications. METHODS: We performed a randomized, double-blind, placebo-controlled clinical trial of three months of vitamin therapy in 200 participants in the Johns Hopkins Lupus Cohort. A baseline was established during the first three months, followed by three months of placebo or active treatment.